A British made target changer sounds interesting - as long as the quality and price stack-up OK.
The Welsh address probably referred to Granville Jones who made RX Target changers. They haven't been produced for a good number of years and Granville may no longer be with us. There isn't a competitive UK option out there.

One thing I forgot to mention about buying direct from Germany. The Haring has an external mains transformer a UK supplier will provide one with a 3 pin plug but from Germany it will have a 2 pin fitting and will require an adapter of suitable 2 pin socket.

Rutty